Introduction: Air pollution caused by changes in the quantity and quality of atmospheric gases. This phenomenon is due to the increased use of fossil fuels in urban areas. Status of natural ENVIronment of the city and the characteristics of the weather elements and phenomena cause congestion, transport and displacement of pollutants, particularly in the central areas of a city. Tehran have Known as a one of the largest city in the world by population. It usually meets critical air quality condition special in central part of the city. In this context, for careful analysis of the physical and natural factors in mitigation or aggravation of air pollution, the micro-scale numerical modeling methods based on a laboratory model of airflow (CFDs) are used. The usefulness of this method is being the quantitative effect of each of the urban fabric and climatic factors in small-scale on spatial and temporal resolution. However, this method can be largely resolves this problem.To evaluate the effects of urban spaces on air pollution in micro-scale, the components such as street width and orientation, mass-produced building model, land use, and green space patterns and classes against atmospheric elements including local prevailing wind direction and intensity, temperature and humidity fluctuations have been discussed. In spite of the fact that numerical modeling can offset most part of micro-scale data deficiencies.

Urban Heat Island (UHI) is considered as one of the major problems in the 21st century posed to human beings as a result of urbanization and industrialization of human civilization. In this study, effects of the variation of physical and geometrical properties of the urban fabric (i.e. cool roofs including green and white roofs and perviousness of paving materials) on the urban micro-climate and outdoor thermal comfort were investigated using 3dimentional urban micro-climate model, ENVI-met. Based on the predicted results, increasing the amount of vegetation and permeable pavements can cool the air temperature down by up to 3 K.

Global warming has become a major challenge of the present century, manifesting in temperature fluctuations and changes in precipitation patterns. Economic growth in urban areas attracts large populations, increasing the demand for housing, energy, water, and food, which in turn leads to various consequences such as higher building and population density, land degradation, and the destruction of natural and agricultural lands. The expansion of industrial factories and air pollution has recently caused significant climatic anomalies in Khorramabad. The accelerating trend of physical development, particularly in the southern regions of the city, further reflects these climatic challenges. According to meteorological data, the average temperature in the city has risen by 0.5°C over the past 30 years. Based on scenarios presented by the Intergovernmental Panel on Climate Change (IPCC), if this trend persists, temperatures could increase by up to 4°C. This study evaluates the relationship between climate change and urban space formation by simulating climatic data and urban ENVIronments at the neighborhood scale using the ENVI-met software. The study analyzes three ten-year development phases (2007, 2012, 2017) by examining temperature, wind speed, and humidity. The findings indicate that semi-open spaces, moderate-density structures, and semi-compact urban fabrics represent the most effective urban forms for mitigating climate change impacts. This structural approach aligns with ENVIronmental design principles tailored to the specific climatic conditions of the study area and the prevailing climate change trends.

Building form has a great influence on energy conservation and a correct architectural design can play a significant role in this field. Shading and its impact on thermal comfort of the residents are among the concepts which are of great importance in the subject of buildings' architectural design with regard to the regional climate. In this paper, an attempt was made to analyze the thermal behavior extent of these semi-open spaces in residential complexes of Mashhad County with the help of ENVI-met software. Therefore, the present paper, which is based on a simulation approach, investigates and analyzes the thermal comfort in semi-open spaces. By comparing different models simulated with ENVI-met software, it can be found out that none of the investigated models achieve the thermal comfort conditions on the day of the summer solstice, but the double-closed model, located on the central side of the building, provides the maximum amount of thermal comfort conditions at a rate of 6 hours on the day of the winter solstice. After this model, the one side closed ones, located in the central side of the building, and three sides closed ones, located in the western side of the building, provide the most thermal comfort time. The weakest models in terms of the duration of providing thermal comfort conditions are the one sided closed and double-closed models located on the west side of the building, which never provide thermal comfort conditions during the summer and winter solstice days.

Introduction: In Iran, there has not been much research and study on the effects of macro-scale climatic factors (especially in the cold climate and cold season); only a few studies on the mental senses of people in urban open spaces have been used in this climate. Is. Therefore, in this paper, we try to investigate the factors affecting cold weather in the cold season in urban streets by examining the thermal comfort index (PMV) and introducing ways to balance the comfort with physical intervention. methodology This study is carried out for typical winter conditions in Chamran Street in Kermanshah (34. 19 N latitude and 47. 7 E) located in the Iran. The climate of this city is cold and mountainous. In this article, February 11 was considered as one of the coldest days of the year (one of the most critical days of the year) to study. The case study has width of 40 meters with a East-West orientation. The height of buildings is between 3 and 39 meters. The ground floor use of this street is mainly commercial and the major materials used in the facade of the buildings, stone and brick, on the floor of the mosaic and concrete Street and in the middle street reflection are also stones. The shadow projection and the Calendar of Climate Needs for Kermanshah City show that there is a need for radiation in the coldest days of the year (from mid-October to March). Therefore, providing sunlight is very necessary. In April, you will need both radiation and shadows. In the months of May to September, shade is needed. Therefore, urban spaces should be designed in a way that meets the needs of people in all seasons. . Several tools were used to collect climatic parameters. In this study, we used an anemometer to measure the wind, and to measure the temperature humidity, humidity and spherical temperature from a multi-function data logger. (Table 1). In order to measure physical parameters, the instruments were placed at a height of 1. 5 m above the ground plane on a stack in the areas under study. The study area was selected according to the variation in the enclosure of several points to investigate and measure the climate parameters. All points were monitored at 5-minute intervals on February 11. . Multi-function data logger measurements with 30 second intervals were automatically recorded from 9-17. Other measurements were done manually due to lack of data logger. This interval is chosen because the greatest number of people in the urban space occurs at this interval In this research, the model of the standard Ashrae 55 is used. This climate model is used to calculate and simulate climate variables in urban space with regular grids accuracy of 0. 5 to 10 meters. Discussion: Observations show that PMV has changed tremendous in comparison to the existent situation, and comfort zone have changed over the course of time, but Tmrt has not changed much. In the intervention, this article did not change much in the mean radiant temperature, but the thermal comfort index has changed considerably. As a result of decreasing a building with two feedback 3-meter and 4 meters in height, the PMV at 9 o'clock from a relatively cold zone to cold zone and has reached to comfortable zone at 10-12 o'clock. Between 13 and 15, the most change is observed, with the PMV zone changing from very cold to cool and relatively cold. Therefore, based on the studies conducted on the basis of studies carried out, in the temperature at 45° to 56° , the street of Chamran is in the comfort zone. Therefore, the design of the spaces should be such as to obtain the highest amount of solar radiation, in order to improve the comfort of the spaces. Therefore, it is suggested that in the future development plan of the city, it should be proposed in the South Front building, to feedback for buildings above 24 meters Because the best way to improve the comfort of Chamran Street in winter is having a 30-32° shadow angle, which PMV will have the best of situation. . Conclusions: Recent studies have shown that the closure of urban canyons affect on the microclimate at the street level. This study, Thermal Comfort in an Urban Street Cold Region Calculated by using physics parameters and evaluation personal variables. This study also had the goal to Calculated Thermal Comfort in an Urban Street Cold Region by software was able to evaluated outdoor thermal perception, One of the output data of ENVI-met is the Predicted Mean Vote (PMV), a thermal comfort index based on a 7-point scale ranging from-3 to +3. This study has examined techniques in responding sufficiently to the urban geometry characteristics, such as H/W ratio and SVF. So, by analyzing field survey and existent and proposed simulation the following results were obtained: 1-To determine the effect of solar radiation on the amount of thermal comfort, the relationship between SVF and PMV is investigated in different locations that are analyzed. In the study area, sections have more opening (higher SVFs) have more potential for solar access in winter, and this improves the comfort of people 2-Based on the simulation carried out on the model, the desired intervention is affected by many changes in the climate and the thermal comfort of the outdoor space. The mean radiant temperature under the influence of some components is significant changes, including the vegetation added to The site is designed to reduce the radiant temperature, which reduces the comfort of people during cold weather. So, reducing the height of high-rise buildings on the street can have an impact on improving the comfort of the street.

Throughout the past century, cities have lost their vital connection with the nature due to the fundamental changes in their functions and physical forms. The development of urbanization and attachment of villages to metropolises in recent years have led to destruction of vegetation in these regions. The importance of identifying the effects of cities on their climates can be indicated only through accurate research and quantitative assessment. The overall increase in air temperature as a result of urbanization is 1-3 degrees Celsius. In stable climatic conditions, however, the air temperature difference between urban and suburban areas can be as high as 10 degrees Celsius. Increasing the amount of vegetation, planting trees, and developing ecological networks are some of the effective passive methods available for improvement of microclimates. Similar methods have been used in the ancient cities of Iran, where the temperature inside the cities has always been lower than that of the surrounding areas due to the utilization of a special type of urban planning which has been capable of providing appropriate climatic conditions at micro scale by controlling climatic elements. Ozgol is one of the northern neighborhoods of Tehran, where green spaces have diminished as a result of the development process and space quality at the centralized focal points has decreased. This study attempted to identify the relationship between green areas and temperature decrease on the hottest day of the year to help improve the quality of the public spaces and increase thermal comfort at the focal points of the neighborhood. This research used a hybrid methodology based on logical reasoning and software-assisted assessment to study a site in the Ozgol neighborhood under two conditions: current status and optimal design. The data on the current situation of the neighborhood were obtained by field measurements, and those on the latter situation were obtained via computer simulation and addition of plants to the area. Then, the PMV model was used for assessment of the comfort conditions and specification of the exact effect of plants on microclimate elements. The two conditions were compared, and the impact of urban design with plants on ENVIronment quality was evaluated. The evaluation criteria included temperature and relative humidity. The measurements were made at a height of 1. 65 meters to prioritize pedestrian comfort. The findings suggested that allocation of a low percentage of city space to greenery can greatly improve microclimatic conditions. The computations indicated that every square meter of green space added to the area under study would expand the comfort zone by 3. 71 times. The results also demonstrated that retention of the amount of relative humidity can reduce air temperature by 1. 5-2 degrees Celsius. The findings of this study highlighted the significance of preserving the current green spaces over the neighborhood and the necessity of avoiding any change in the land use of the remaining gardens (about 6, 000 m2 in the 4-hectare area of the site). The computations also showed that addition of the existing green spaces over the area by 2. 69% can expand the area within the range of thermal comfort to twice as wide as the pre-intervention area. One the other hand, the issue of global warming, the 1-degree rise in the world’ s temperature during the past century, highlights the value and significance of this 1. 5-degree temperature decrease. Thus, it is possible to make significant changes through extension of the results of this study to a larger scale to involve the entire city.

Background and Objective: Since modifying the outdoor condition has an impact on the indoor conditions, the objective of the present research is to study the central courtyard as a passive solar strategy to create microclimate on a scale of an urban block in Tehran climate. By creating microclimate in the vicinity of the building, its thermal performance could be thus enhanced. In addition to comparing temperature in the courtyard with that of the outside the building, this research also studied the influence of water and plants in forming microclimate. method: Analysis method is composed of investigating case studies, field measurements and simulation. Findings: According to the measurements conducted in four directions of the courtyard under study and comparing them with the temperature in the lateral street and the mean temperature recorded in Mehrabad Weather Station in the same time frame, the mean temperature of the courtyard was 4. 52 ° C less than that of the street and 4. 01 ° C less than that of Mehrabad Weather Station. Comparing results obtained from cold seasons show that temperature of the courtyard was 0. 9 ° C more than that of the outer space and 1. 4 ° C more than that recorded in Mehrabad Weather Station. Consequently, Memar Bashi Theological Seminary courtyard has functioned as a microclimate. Discussion and Conclusion: with an approximate difference of 0. 3° C, simulation results confirm the microclimate function of Memar Bashi Theological Seminary courtyard. Comparisons between the influence of water and plants have also indicated that in the hot seasons, plant coverage could decrease the temperature by 0. 9 ° C more than what water does.

The thermal characteristics of an area are not affected lonely by climatic conditions and its seasonal changes,other factors such as urban geometry, vegetation and aquatic elements can be effective in improving thermal comfort. Improving thermal comfort is one of the important goals in designing urban open spaces. The heat island is an effective factor in the thermal comfort of the urban sub-climate and the vegetation is also effective in controlling the heat island. One of the effective solutions in controlling the heat island of open spaces is to be aware of the different characteristics of different vegetation that control the impact of this phenomenon. The aim of this study was to investigate the impact and importance of vegetation and their height in the topography of the site, as one of the most widely used and effective tools in designing the quality of thermal comfort in designing part of the urban open space of Nazhvan Park in the west of the city. Isfahan and provide an optimal model of vegetation height in topography. Data collection method, field, analytical and quantitative, with comparative analysis method of proposed design options using simulation in ENVI-met software (4. 4. 4) in nine different vegetation patterns With a fixed plant type in ten different points of the site on June 15, 2017, and the criteria for measuring thermal comfort at the site are: air temperature, relative humidity, air flow and average radiant temperature and the index used in This study is PMV, which is one of the most comprehensive methods for estimating thermal comfort. The results indicate that a large number of trees, on the one hand, and higher trees on the other, as well as changes in topographic height, are very effective in changing and improving thermal comfort.

Wind erosion is considered as one of the main processes of land degradation in different parts of the world. Among the most effective ways to control wind erosion is to cover land surface with natural vegetation area. In this study, 3 replica soil samples were collected, at a depth of 0-3 cm, from various land uses in Dehloran, Ilam Province, Iran. Physical and chemical characteristics of soil samples were determined in the laboratory to allow the application of the ENVI_met Headquarter model commonly used to design biological windbreak. The threshold friction velocity (TFV) is the basic parameter for effective construction of a windbreak. To determine its values, a wind tunnel test was conducted. Based on simulation results with the pattern designed with Prosopis juliflora species, it was observed that the wind speed decreased in front of the windbreak but returned to the initial speed at a larger distance behind the windbreak. Therefore, the designed windbreak for this species is able to reduce the wind speed to a far distance while in the designed windbreak with Haloxylon aphyllum species the wind returns to the initial speed within a shorter distance. According to the results, the wind speed reduction is directly related to the height of windbreak. Moreover, the designed windbreak with P. juliflora species, more effectively reduce the wind speed and protect longer distances behind the windbreak; thus it can be proposed as a suitable windbreak for the study area.